Improvement in parallel rulers



UNITED STATES PATENT OFFICE.

GUSTAV BLUNGK, OF NEW YORK, N. Y.

IMPROVEMENT IN PARALLEL RULERS.4

Specification forming part of Letters Patent No. 141,029, dated J nly 22, 1873; application filed May 10, 1873.

To all whom t may concern: I

of the same with part-s cut ofi, Fig. 3, a vertical transverse section through the central part on the line c c, Fig. 1; Fig. 4, a vertical transverse section through one end of the guide-frame on the line .r x, Fig. l; and Fig. 5, a bottom view of the end of the sliding piece.

Similar letters of reference indicate corresponding parts.

The object of my invention is to construct for draftsmen, lithographers, and others, an improved parallel ruler which is accurate in its operation, rapid in motion, and capable of various applications in drafting. My invention consists in a main slide-piece, with suitable set-screws, moving in a guide-frame carrying the adjustable ruler, and acted upon by a band-spring applied to a wedge-like thumbpiece, which produces alternately, by the pressing and releasing of the controlling iinger, the required parallel motion of the ruler.

In the drawing, A represents the guideframe, of suitable material and finish, consist ing ot' the central part and the end pieces B', of rectangular shape, and longitudinallyr connected by rodsb. rIhe central part B is larger than the side pieces B', and is cast in one piece with the vertically-projecting inclined bearing C, which is placed centrally to part B in the longitudinal axis of frame A.

lThe shorter sides of bearing C are tapered downward, and part B recessed at the lower end thereof. A slot,'a, isl provided at one oi' the longest sides of bearing C to admit leverhand d, which has its fulcrum at e, and moves with its pointed end on scale j', marked on part B. The end of lever d, inside of bearing (l, is slotted to be placed on and move with vertical pin D of sliding ruler E. A set-screw, F, placed at the opposite side of part B symmetrically to scale f, acts on the ruler G, of suitable len gth and material, which can thereby be adjusted radially around screw F. Spiral springs g are applied to lugs g at the shorter sides of bearing C, in the direction of the longitudinal axis of frame A, having eye-shaped ends, which can be placed over vertical pins h of sliding piece E. The side pieces B of frame A are provided at the lower edges with narrow leather or India-y rubber bands t', which are slipped over rodsu and ,attached suitably to pieces B. They serve as the resting-points of the frame A on the drawing-paper, and glide easily over the same, giving, also, a sufcient amount ot friction to hold the frame stationary when not operated upon. A screw, Z, is applied to the center of each piece B', with the head downward, which is placed in the longitudinal slot Z1 of the metallic top end plate E of sliding piece'E, suspending and guidingit exactly in the longitudinal axis of frame A. The sliding piece E, in the shape of a common ruler, is

somewhat longer than frame A, of wood, India rubber, or other suitable material. It carries centrally the vertical pin or bolt D, projecting upward, through bearing C and equidistant fromit, on both sides of B, the hard wood or rubber standards or projections m having vertical pins h, and horizontal'set-'screws n passing longitudinally through projections in. The ends of these set-screws n act on projections n of part B, and may be set so as to work the ruler in either direction, and produce the required distance of the parallel lines.

The most frequently used distances may be laid off on scale f, andthe set-screws n adjusted to correspond. The end top plates E of sliding piece E have, besides slots Z1, wider slots Z2, also equidstant from central pin l),

for the purpose of admitting thereinthe ends of the band-springs H of cone I. The sliding piece E is recessed below plates E', and rectangular pieces o are placed loosely therein below slots Z2, and held in position by pieces p of chamois leather, or other suitable material, glued or otherwise applied to the lower side of sliding piece E. The steel band-spring H is riveted to the conical center piece I, which acts by the pressure on the rivets q, serving as finger-rests, against the conical sides of bearing C. j

A vertical central perforation, r, admits the pin D of sliding piece E. By pressing the wedge I down, the ends of the band-spring H bear on the. loose rectangles o, so that by the friction of the leather pieces p the slidingr piece E is held firmly on the drawing-paper. The side-thrust of the wedge I against the inclined bearing G causes the forward gliding of frame A in slots ll, so that the parallel lines can be drawn -along the ruler G. The pressure oi' the finger is then removed. and the immer'iate forward motion of sliding piece E is produced by the spiral spring g being on the same side as the tingererest q. The other spring is disconnected and applied, when the instrument is used in opposite direction.

By fastening firmly the ends of ruler G to some fixed point, radially-inclined lines for cones, &c., can be produced, as the instrument is compelled to move in a circle around the fixed center. The parallel ruling is accomplished by the use of this instrument in a quick and superior manner, as it works accurately and satisfactorily.

Having thus described my invention, I claim as new and desire to secure by Letters Patent- 1. The frame A, provided with bearing C, pin D, slide E, ruler G, spring H, with tapering key I, and rest o, as and for the purpose described.

2. The main frame A, composed of center part B and side parts B', connected by rods,b, and arranged to slide upon each other, substantially as set forth.

3. The central part B, having inclined bearings C with lugs g. projections u', springs g, slot a, lever d, scale f, set-screw F, and ruler G, substantially as described.

4. The side pieces B', having rests z' and guide-screws l, as set forth.

5. The' sliding piece E, having central pin D, standards m, With pins 7i and set-screws u, and top plates E', for the purpose described.

6. The top plate E', having the slots Z1 for guiding slide-piece E in the direction of' the longitudinal axis, and slots Z2 for spring H, as set forth.

7. The sliding piece E, being recessed, in combination with rectangular pieces o below slots Z2 and leather bottom strips 11, as set forth.

GUSTAV BLUNOK.

Witnesses: l

PAUL GOEPEL, T. B. MosHER. 

